Compression ignition engines



. July 14, 1964 L. PERAS COMPRESSION IGNITION mamas Filed May 21 i963 INV ENT OR LUCIEN PRAs U m M ?i\\\ l k VIII!!! M ATTORNEYS United States Patent Claims priority, application France Dec. 28, 1959 4 Claims. (Cl; 123-32) This application is a continuation in part of my copending application Serial No. 75,764 filed on December 14, 1960, now abandoned.

This invention relates to compression ignition engines. In compression ignition or diesel engines, fuel is injected into the cylinders and one kind of such engines. has a separate pre-combustion chamber mounted in the cylinder head, this chamber being connected to the main cylinder by a properly directed transfer passage ensuring a strong turbulence in the chamber during thecompression cycle.

According to the present invention there is provided a compression-ignition engine comprising a cylinder, a cylinder head, a pre-combustion chamber mounted in the cylinder head and including separate upper and lower portions, said upper portion being spaced, from the cylinder head so as to be heat insulated therefrom by air in the space whereby the upper portion in operation provides a hot vault, a fuel injector arranged to direct fuel jets against the inner face of said vault at a very small angle of incidence with respect thereto, and an air transfer passage between said cylinder and said chamber, said air transfer passage opening into said chamber substantially tangentially with respect to a wall thereof.

Thus, in the present engine, whilst the conventional configuration of the pre-combustion chamber is maintained, a substantial portion of the wall of this chamber is heat-insulated from the cooling system of the engine with a view to ensuring a smoother and more silent operation of the engine, a part of the insulated portion constituting, during operation, a hot vault receiving jets of fuel from the injector. The fuel is deposited, spread out and put in reserve on the hot vault, then vaporized by this vault and carried away by the air issued from the transfer passage.

According to a preferred embodiment of the invention the pre-combustion chamber proper consists of two portions separated by a horizontal joint, the upper portion being isolated from the cooling system by a thin sheet of This invention is also concerned with the specific arrangement of the injector and the heater plug in the precombustion chamber.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which:

FIGURE 1 is a fragmentary sectional view of a part of a first form of engine, and

FIGURE 2 is a similar view of an alternative form of engine.

Referring to the drawing and more particularly to FIG- URE 1, it will be seen that the cylinder head 1 of the engine has a separate pre-combustion chamber consisting of two separate portions, that is, an upper portion 2 and a lower portion 3 separated by a horizontal joint. An injector secured on the cylinder head 1 as in conventional arrangements has an injection nozzle 4 (which is the only visible part of the injector in this figure) extending through the upper portion 2 of the combustion chamber. The lower portion 3 of this pre-combustion chamber includes a transfer passage 5 lying at a relatively acute angle in relation to the cylinder head joint. This passage 5 extends substantially from one end of a generatriX of the cylinder and is approximately tangential at 6 to the cup of the lower portion 3 which contacts the cooled walls of ice the cylinder head through a bearing face 7 and shoulder 8. The face of the outer wall 10 of the upper portion 2 is curved, it being centered at 9, and there is provided between the outer wall 10 and the inner Wall 11 of the cylinder head 1 a small play or air space i sufficient for heat-insulating the upper portion 2 of the pre-combustion chamber. The ratio of the area of the outer surface of the injection chamber which is not in contact with the cylinder head 1 to the total outer surface area of the chamber determines, during operation, the temperature of inner walls 15 and 13 of the chamber. A heater plug 12 has its electrode located in an opening formed in the upper portion 2 of the pre-combustion chamber at a properly selected position, after the injection nozzle 4 on the path of the combustion air, that is, downstream of the injector having regard to the direction in which fuel jets issue from the injector so that jets of fuel as they issue from the injection nozzle 4 are directed substantially in the directionof the point where the electrode of the plug 12 communicates with the pre-combustion chamber.

The upper portion 2 of the pre-combustion chamber constitutes a vault and the portion of this vault which is located between the injection nozzle 4 and the point where the electrode of the plug 12 communicates with the pre' combustion chamber constitutes a preferably slightly flattened wall 15.

The direction of the tangential air transfer passage 5 is such that the combustion air leaving the passage 5 passes before the injection nozzle 4, follow the fuel jets along the wall 15 and passes before the point where the electrode of the plug 12 communicates with the pre-combustion chamber.

Owing to the fact that the fuel jets are substantially directed against the point where the electrode of the plug 12 cormnunicates with the injection chamber and that the vault comprises a wall 15 located between the injection nozzle 4 and said point, the fuel jets which strike the hot inner wall 15 of the vault can only do it at a very small angle of incidence, that is they are directed approximately tangentially with respect to this wall. Accordingly, the path taken by the jets of fuel is diagrammatically indi cated by dotted lines P.

It will be noted that the walls 14, like the wall 15 of the pre-combustion chamber, is preferably slightly fiattened.

The operation of the engine is as follows. To start the engine in a cold air medium, current is supplied to the plug 12. It is recognised that a starting plug having a heating resistance such as the plug 12 is not a suflicient source of heat notably to increase the temperature of an enclosed space such as the pre-combustion chamber. Thus the walls 13 and 15, at starting, are too cold to perform their normal function of vaporizing and igniting the fuel which comes into contact with them. As a consequence of the specific position of the heater plug 12 open;- ing into the vault in the upper portion 2 of the pre-combustion chamber, a hot spot is obtained in this vault by the electrode of said plug, so that a small amount of fuel is projected by the injector on this hot spot, which is sufficient for starting the combustion in a cold air medium, since the walls likely to receive fuel projections are still too cold to vaporize and ignite this fuel under these circumstances.

After the starting, during the normal working of the engine, the wall 15 of the upper portion 2 forms a hot vault receiving the fuel jets from the injector under a small angle of incidence, thereby ensuring a smooth and silent operation of the engine.

In the alternate embodiment illustrated in FIG. 2 the relative positions of the injection nozzle 4 and starting or heater plug 12 are inverted, but it will be seen that the air transfer passage 5 is also arranged differently so that the air turbulence is inverted likewise. In this case the injection nozzle 4 is in the upper position and the heater plug 12 is disposed laterally, contrary to the arrangement shown in FIG. 1.

It may also be noted that in this alternate embodiment the direction of flow of the combustion air is not appreciably modified even after its passage before the fuel injection nozzle 4. Thus, it will follow the fuel jet in a more efiicient and reliable manner.

Of course, various modifications may be brought to the embodiments shown and described herein without departing from the basic principles of the invention as set forth in the appended claims.

I claim:

1. A compression-ignition engine comprising a cylinder, a cylinder head, a pre-combustion chamber mounted in the cylinder head and including separate upper and lower portions, said upper portion being spaced from the cylinder head so as to be heat insulated therefrom by air in the space whereby the upper portion in operation provides a hot vault, said upper portion having a substantially flat inner surface, a fuel injector arranged to direct fuel jets against the inner face of said vault at a small angle of incidence with respect thereto, and an air transfer passage between said cylinder and said chamber, said air transfer passage opening into said chamber substantially tangentially with respect to a wall thereof and in such a direction that the air delivered to said chamber through said transfer passage during operation passes over said fuel injector before contacting said inner face.

2. A compression-ignition engine as claimed in claim 1,

wherein a heater plug is mounted in said upper portion so as to be downstream of the injector having regard to the direction in which the fuel jets issue from the injector.

3. A compression-ignition engine as claimed in claim 1, wherein said air transfer passage extends substantially from one end of a generatrix of said cylinder and is substantially tangential to a Wall of said lower portion of said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,984,836 Kreis Dec. 18, 1934 2,003,311 Ricardo June 4, 1935 2,021,744 Perkins Nov. 19, 1935 2,066,228 Ricardo Dec. 29, 1936 FOREIGN PATENTS 303,338 Italy Nov. 29, 1932 579,214 France July 26, 1924 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,140 ,697 July 14 1964 Lucien Peras that error appears i that the said Letters Pa It is hereby certified n the above numbered pat ent requiring correction and tent should read as corrected below.

on, line 6, for 1959" read In the heading to the printedspecificati "Claims priority, application France Dec. 28,

- Claims priority, application France, Dec. Patent 1 ,253 ,280 Oct. 15, 1960 841 ,328, Paten Signed and sealed this 15th day of June 1965 (SEAL) Attcst:

ERNEST w. SWIDER EDWARD J. BRENNER Commissioner of Patents Altcsting Officer 

1. A COMPRESSION-IGNITION ENGINE COMPRISING A CYLINDER, A CYLINDER HEAD, A PRE-COMBUSTION CHAMBER MOUNTED IN THE CYLINDER HEAD AND INCLUDING SEPARATE UPPER AND LOWER PORTIONS, SAID UPPER PORTION BEING SPACED FROM THE CYLINDER HEAD SO AS TO BE HEAT INSULATED THEREFROM BY AIR IN THE SPACE WHEREBY THE UPPER PORTION IN OPERATION PROVIDES A HOT VAULT, SAID UPPER PORTION HAVING A SUBSTANTIALLY FLAT INNER SURFACE, A FUEL INJECTOR ARRANGED TO DIRECT FUEL JETS AGAINST THE INNER FACE OF SAID VAULT AT A SMALL ANGLE OF INCIDENCE WITH RESPECT THERETO, AND AN AIR 